Been sailing for 50 years and can count the number of vessels with no state required bow alpha-numerics - on one hand.

Documented vessels may not display state registration numbers:

"Vessels may ONLY be identified as either a State Registered Vessel or a Federally Documented Vessel - BUT NOT BOTH. When a vessel becomes Federally Documented, the State Registration Numbers and Letters must be removed. However the State Validation Sticker showing proof of paying sales tax may still be displayed on the vessel in accordance with the individual state’s regulations."